Dental instrument.



T. D. CRAIG.

DENTAL INSTRUMENT.

APPLICATION FILED APE. 30.1914. RENEWED DEC. 19, 1914.

' Patented Mar. 23, 1915.

THOMAS ID. CRAIG,

0F ALBIA, IOWA.

DENTAL INSTRUMENT.

Application filed. April 30, 1914, Serial N 0. 835,425.

To all whom it may concern:

Be it known that I, THOMAS D. CRAIG, a citizen of the United States of America, re siding at Albia, in the county of Monroe and State of Iowa, have invented certain new and useful Improvements in Dental Instruments, of which the following is a specification.

The present invention relates to improvements in dental instruments, and is designed especially for the purpose of perfecting the dental instrument disclosed in my application for patent Serial Number 802,791, filed January 17, 1914;, in which an improvement is disclosed for use in the removal of crowns, bridges, bands and other artificial surfaces afixed to teeth.

The present disclosure contemplates certain improvements and enhances the value of the instrument both as to efliciency and operation, as will be hereinafter pointed out.

Figure 1 is a plan view of the instrument according to this invention. Fig. 2 is a side elevation of the instrument. Fig. .3 is a front end elevation showing the application of the instrument to a tooth. Fig. 4 is an under side plan view of the actuating lever for withdrawing a. crown from a tooth. Fig. 5 is a view showing in section one of the heads with a slidable jaw therein, constructed according to the principles of the present invention. Fig. 6 is a perspective View of one of the slidable or movable clamping jaws. Fig. 7 is a perspective view of one of the heads showing it as detached. Fig. 8 is a side view of the screw which forms the pivot for the two movements of the clamping jaws.

In the drawings I have illustrated the principles of the common type of pliers or scissors in the pivoted handles 1 and 2, of which the screw or threaded pin 3 forms the coupling member. In Fig. 8 it will be seen that the pin 3 is formed with a head 1 and is also formed with a spherical head or ball 5, and an angular groove 6 between said ball and the threaded portion of the screw. The two levers 1 and 2 in addition to being operable by hand are provided with a power operating screw bar 7 swiveled at 8 in the lever arm 1, and it is passed through an enlarged opening in the arm 2 and provided with a thumb nut 9, which is adapted to bear upon the outer face of the lever arm 2 when drawing the two arms together.

The short arms of the levers 1 and 2 are Specification of Letters Patent.

Patented Mar. 23, 1915.

Renewed December 19, 1914. Serial No. 878,185. I

provided with duplicate heads 10 and Hangularly disposed and depending from the levers at a spaced distance in order to provide an opening 12 between them. Each head is provided with a dove tail groove 18 extending from end to end and open at the top and bottom, and these grooves form mortises for guiding the tenons of the movable jaws 14. The lower endof each head is forked as shown, and the movable jaws ll are adapted to move between these forked ends. Each movable jaw is provided with a curved lower finger 15 and the upper spherical head 16, and its tenon 17 is formed by a portion of the spring 18 which is adapted to bear against the vertical wall of the slot 13, and normally press the jaw inwardly toward the tooth.

The jaws 1 1 are slidable in the mortises 13, and they are moved by means of a spring pressed actuating lever 19 which is fulcrumed by means of its socket 20 in the arm over the ball or head 5 of the pivot screw 3. A set screw 21 is threaded into an opening in the lever 19 and engages in the groove 6 of the screw to prevent displacement of the fulcrum screw.

The lever 19 is connected to the heads 10 and 11 through the medium of the separated grooves 22 formed in the forks 23 at the end of the lever 19. V

The actuating lever 19 is operated or moved on its pivot 5 by means of a thumb nut 24 on the swiveled stem 25 which is passed through an opening 26 in the end of the actuating lever 19. The lower end of the stem 25 is perforated, and the screw bar 7 is passed therethrough, and between the screw bar and washer 26 on the stem 25, a coiled spring 27 is located and which is adapted to return the lever 19to normal position. In Fig. 1 it will be seen that there are two coil springs 28 and 29 on the screw bar 7, one at each side of the stem 25, and tending to hold the lever arms 1 and 2 distended, and the stem 25, equidistant from 1evers 1 and 2.

From the above description taken in connection with the drawings it is evident that the instrument is capable of two distinct movements 2'. c. the clamping of the grasping jaws on the tooth and then the pulling or sliding movementof the engaged clutch fingers 15 to withdraw the crown from the tooth. The former of these movements is accomplished by drawing the two lever arms 1 and 2 together by means of the nut wing, into the position of Fig. 3 to grip the tooth as in a vise and form an anchor or support for the further movements of the operative parts of the device. The slidable jaws or clutches are shown in just the proper position to dislodge the crown, and this dislodgment is accomplished by means of the actuating lever 19, which, through turning its wing nut is moved on its fulcrum and causes the slidable jaws to be moved and guided through the slotted heads of the levers l and 2, and the fingers or claws of the slidable jaws engaging under the crown draw the crown from engagement with the tooth. The vise or clamping jaws may then be loosened and the instrument withdrawn from the month carrying the dislodged crown with it, as will be readily understood.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is

1. The combination in a dental instrument having pivoted lever arms and spaced angular heads thereon, of movable clutching jaws in said heads, means urging said jaws to move toward each other, and means for moving said jaws in a plane perpendicular to the before mentioned movement.

2. The combination in a dental instrument having pivoted lever arms and spaced angular heads thereon, of movable clutching jaws in said heads, springs in the heads urging said jaws to move toward each other, and means for moving said jaws in a plane perpendicular to the before mentioned move-- ment. I

3. The combination in a dental instrument having pivoted levers held apart by springs and spaced angular heads thereon, of movable clutching jaws in said heads, means urging said jaws to move toward each other, and means for moving said aws in a plane perpendicular to the before mentioned movement.

4-. The combination in a dental instrument having pivoted levers held apart by springs and spaced angular heads thereon, of movable clutching jaws in said heads, springs in the heads ur ing said jaws to move toward each other, and means for movin said jaws in a plane perpendicular to the before mentioned movement.

in testimony whereof I a'l'lix my signature in presence of two witnesses.

THOMAS D.

' l. BURDAN.

Corliss e1 thta patent xnay be obtained for five cents each, by addressing the Commissioner f Patents.

Washington, 12. 1. 

